General Information About Wilms Tumor and Other Childhood Kidney Tumors

Childhood kidney tumors are diseases in which malignant (cancer) cells form in the tissues of the kidney.

There are two kidneys, one on each side of the spine, above the waist. Tiny tubules in the kidneys filter and clean the blood. They take out waste products and make urine. The urine passes from each kidney through a long tube called a ureter into the bladder. The bladder holds the urine until it passes through the urethra and leaves the body.

There are many types of childhood kidney tumors.

Wilms Tumor

In Wilms tumor, one or more tumors may be found in one or both kidneys. Wilms tumor may spread to the lungs, liver, bone, brain, or nearby lymph nodes. In children and adolescents younger than 15 years old, most kidney cancers are Wilms tumors.

Renal Cell Cancer (RCC)

Renal cell cancer is rare in children and adolescents younger than 15 years old. It is much more common in adolescents between 15 and 19 years old. Children and adolescents are more likely to be diagnosed with a large renal cell tumor or cancer that has spread. Renal cell cancers may spread to the lungs, liver, bone, or lymph nodes. Renal cell cancer may also be called renal cell carcinoma.

Rhabdoid Tumor of the Kidney

Rhabdoid tumor of the kidney is a type of kidney cancer that occurs mostly in infants and young children. It is often advanced at the time of diagnosis. Rhabdoid tumor of the kidney grows and spreads quickly, often to the lungs or brain.

Children with a certain change in the SMARCB1 gene can also have tumors grow in the kidney, brain, or soft tissues. These children are checked regularly to see if a rhabdoid tumor has formed in the kidney or the brain:

• Children from birth or diagnosis to 5 years old have an MRI of the brain and spine and an ultrasound of the abdomen every 3 months.

Clear Cell Sarcoma of the Kidney

Clear cell sarcoma of the kidney is an uncommon kidney cancer that may spread to the bone, lungs, brain, liver, or soft tissue. It occurs most often before age 3 years. It may recur (come back) up to 14 years after treatment, often in the brain or lung.

Congenital Mesoblastic Nephroma

Congenital mesoblastic nephroma is a tumor of the kidney that is often diagnosed during the first year of life or before birth. It is the most common kidney tumor found in infants younger than 6 months old and is found more often in males than in females. It can usually be cured.

Ewing Sarcoma of the Kidney

Ewing sarcoma (previously called neuroepithelial tumor) of the kidney is rare and usually occurs in young adults. This cancer grows and spreads to other parts of the body quickly.

Primary Renal Myoepithelial Carcinoma

Primary renal myoepithelial carcinoma is a rare type of cancer that usually affects soft tissues, but sometimes forms in the internal organs (such as the kidney). This type of cancer grows and spreads quickly.

Cystic Partially Differentiated Nephroblastoma

Cystic partially differentiated nephroblastoma is a very rare type of Wilms tumor made up of cysts.

Multilocular Cystic Nephroma

Multilocular cystic nephromas are benign tumors made up of cysts and are most common in infants, young children, and adult women. These tumors can occur in one or both kidneys.

Children with this type of tumor also may have pleuropulmonary blastoma, so imaging tests that check the lungs for cysts or solid tumors are done. Since multilocular cystic nephroma may be an inherited condition, genetic counseling and genetic testing may be considered. See the PDQ summary about Childhood Pleuropulmonary Blastoma Treatment for more information.

Primary Renal Synovial Sarcoma

Primary renal synovial sarcoma is a cyst-like tumor of the kidney and is most common in young adults. These tumors grow and spread quickly.

Anaplastic Sarcoma of the Kidney

Anaplastic sarcoma of the kidney is a rare tumor that is most common in children or adolescents younger than 15 years of age. Anaplastic sarcoma of the kidney often spreads to the lungs, liver, or bones. Imaging tests that check the lungs for cysts or solid tumors may be done. Since anaplastic sarcoma may be an inherited condition, genetic counseling and genetic testing may be considered.

Nephroblastomatosis is not cancer but may become Wilms tumor.

Sometimes, after the kidneys form in the fetus, abnormal groups of kidney cells remain in one or both kidneys. In nephroblastomatosis (diffuse hyperplastic perilobar nephroblastomatosis), these abnormal groups of cells may grow in many places inside the kidney or make a thick layer around the kidney. When these groups of abnormal cells are found in a kidney after it was removed for Wilms tumor, the child has an increased risk of Wilms tumor in the other kidney. Frequent follow-up testing is important at least every 3 months, for at least 7 years after the child is diagnosed or treated.

Having certain genetic syndromes, other conditions, or environmental exposures can increase the risk of Wilms tumor.

Anything that increases the risk of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn't mean that you will not get cancer. Talk to your child's doctor if you think your child may be at risk.

Wilms tumor may be part of a genetic syndrome that affects growth or development. A genetic syndrome is a set of signs and symptoms or conditions that occur together and is caused by certain changes in the genes. Certain conditions or environmental exposures can also increase a child's risk of developing Wilms tumor. The following have been linked to Wilms tumor:

• WAGR syndrome (Wilms tumor, aniridia, abnormal genitourinary system, and mental disability).
• Denys-Drash syndrome (abnormal genitourinary system).
• Frasier syndrome (abnormal genitourinary system).
• Beckwith-Wiedemann syndrome (abnormally large growth of one or more body parts, large tongue, umbilical hernia at birth, and abnormal genitourinary system).
• A family history of Wilms tumor.
• Aniridia (part or all of the iris, the colored part of the eye, is missing).
• Isolated hemihyperplasia (abnormally large growth of one or more body parts).
• Urinary tract problems such as cryptorchidism or hypospadias.
• The child's mother being exposed to pesticides while she was pregnant.

Tests are used to screen for Wilms tumor.

Screening tests are done in children with an increased risk of Wilms tumor. These tests may help find cancer early and decrease the chance of dying from cancer.

In general, children with an increased risk of Wilms tumor should be screened for Wilms tumor every 3 months until they are at least 8 years old. An ultrasound test of the abdomen is usually used for screening. Small Wilms tumors may be found and removed before symptoms occur.

Children with Beckwith-Wiedemann syndrome or hemihyperplasia are also screened for liver and adrenal tumors that are linked to these genetic syndromes. A test to check the alpha-fetoprotein (AFP) level in the blood and an ultrasound of the abdomen are done until the child is 4 years old. An ultrasound of the kidneys is done between the ages of 4 and 7 years old. A physical exam by a specialist (geneticist or pediatric oncologist) is done two times each year. In children with certain gene changes, a different schedule for ultrasound of the abdomen may be used.

Children with aniridia and a certain gene change are screened for Wilms tumor every 3 months until they are 8 years old. An ultrasound test of the abdomen is used for screening.

Some children develop Wilms tumor in both kidneys. These often appear when Wilms tumor is first diagnosed, but Wilms tumor may also occur in the second kidney after the child is successfully treated for Wilms tumor in one kidney. Children with an increased risk of a second Wilms tumor in the other kidney should be screened for Wilms tumor every 3 months for up to 8 years. An ultrasound test of the abdomen may be used for screening.

Having certain conditions may increase the risk of renal cell cancer.

Renal cell cancer may be related to the following conditions:

• Von Hippel-Lindau disease (an inherited condition that causes abnormal growth of blood vessels). Children with Von Hippel-Lindau disease should be checked yearly for renal cell cancer with an ultrasound of the abdomen or an MRI (magnetic resonance imaging) beginning at age 8 to 11 years.
• Tuberous sclerosis (an inherited disease marked by noncancerous fatty cysts in the kidney).
• Familial renal cell cancer (an inherited condition that occurs when certain changes in the genes that cause kidney cancer are passed down from the parent to the child).
• Renal medullary cancer (a rare kidney cancer that grows and spreads quickly).
• Hereditary leiomyomatosis (an inherited disorder that increases the risk of having cancer of the kidney, skin, and uterus).

Prior chemotherapy or radiation therapy for a childhood cancer, such as neuroblastoma, soft tissue sarcoma, leukemia, or Wilms tumor may also increase the risk of renal cell cancer. See the Second Cancers section in the PDQ summary about Late Effects of Treatment for Childhood Cancer for more information.

Treatment for Wilms tumor and other childhood kidney tumors may include genetic counseling.

Genetic counseling (a discussion with a trained professional about genetic diseases and whether genetic testing is needed) may be done if the child has one of the following syndromes or conditions:

• A genetic syndrome or condition that increases the risk of Wilms tumor.
• An inherited condition that increases the risk of renal cell cancer.
• Rhabdoid tumor of the kidney.
• Multilocular cystic nephroma.
• Anaplastic sarcoma of the kidney.

Signs of Wilms tumor and other childhood kidney tumors include a lump in the abdomen and blood in the urine.

Sometimes childhood kidney tumors do not cause signs and symptoms and the parent finds a mass in the abdomen by chance or the mass is found during a well-child health check-up. These and other signs and symptoms may be caused by kidney tumors or by other conditions. Check with your child's doctor if your child has any of the following:

• A lump, swelling, or pain in the abdomen.
• Blood in the urine.
• High blood pressure (headache, feeling very tired, chest pain, or trouble seeing or breathing).
• Hypercalcemia (loss of appetite, nausea and vomiting, weakness, or feeling very tired).
• Fever for no known reason.
• Loss of appetite.
• Weight loss for no known reason.

Wilms tumor that has spread to the lungs or liver may cause the following signs and symptoms:

• Cough.
• Blood in the sputum.
• Trouble breathing.
• Pain in the abdomen.

Tests that examine the kidney and the blood are used to diagnose Wilms tumor and other childhood kidney tumors.

The following tests and procedures may be used:

• Physical exam and health history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.
• Complete blood count (CBC): A procedure in which a sample of blood is drawn and checked for the following:
  • The number of red blood cells, white blood cells, and platelets.
  • The amount of hemoglobin (the protein that carries oxygen) in the red blood cells.
  • The portion of the blood sample made up of red blood cells.
• Blood chemistry studies: A procedure in which a blood sample is checked to measure the amounts of certain substances released into the blood by organs and tissues in the body. An unusual (higher or lower than normal) amount of a substance can be a sign of disease. This test is done to check how well the liver and kidneys are working.
• Renal function test: A procedure in which blood or urine samples are checked to measure the amounts of certain substances released into the blood or urine by the kidneys. A higher or lower than normal amount of a substance can be a sign that the kidneys are not working as they should.
• Urinalysis: A test to check the color of urine and its contents, such as sugar, protein, blood, and bacteria.
• Ultrasound exam: A procedure in which high-energy sound waves (ultrasound) are bounced off internal tissues or organs and make echoes. The echoes form a picture of body tissues called a sonogram. An ultrasound of the abdomen is done to diagnose a kidney tumor.
• CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, such as the chest, abdomen, and pelvis, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye is injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.
• MRI (magnetic resonance imaging) with gadolinium: A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body, such as the abdomen. A substance called gadolinium is injected into a vein. The gadolinium collects around the cancer cells so they show up brighter in the picture. This procedure is also called nuclear magnetic resonance imaging (NMRI).
• X-ray: An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body, such as the chest and abdomen.
• PET-CT scan: A procedure that combines the pictures from a positron emission tomography (PET) scan and a computed tomography (CT) scan. The PET and CT scans are done at the same time on the same machine. The pictures from both scans are combined to make a more detailed picture than either test would make by itself. A PET scan is a procedure to find malignant tumor cells in the body. A small amount of radioactive glucose (sugar) is injected into a vein. The PET scanner rotates around the body and makes a picture of where glucose is being used in the body. Malignant tumor cells show up brighter in the picture because they are more active and take up more glucose than normal cells do.
• Biopsy: The removal of cells or tissues so they can be viewed under a microscope by a pathologist to check for signs of cancer. The decision of whether to do a biopsy is based on the following:
  • The size of the tumor.
  • The stage of the cancer. If the tumor appears to be resectable or stage I or stage II Wilms tumor, a biopsy is not done to avoid tumor cells being spread during the procedure.
  • Whether cancer is in one or both kidneys.
  • Whether imaging tests clearly show the cancer.
  • Whether the patient is in a clinical trial.
  A biopsy may be done before any treatment is given, after chemotherapy to shrink the tumor, or after surgery to remove the tumor.

Certain factors affect prognosis (chance of recovery) and treatment options.

The prognosis and treatment options for Wilms tumor depend on the following:

• How different the tumor cells are from normal kidney cells when looked at under a microscope.
• The stage of the cancer.
• The type of tumor.
• The age of the child.
• Whether the tumor can be completely removed by surgery.
• Whether there are certain changes in chromosomes or genes.
• Whether the cancer has just been diagnosed or has recurred (come back).

The prognosis for renal cell cancer depends on the following:

• The stage of the cancer.
• Whether the cancer has spread to the lymph nodes.

The prognosis for rhabdoid tumor of the kidney depends on the following:

• The age of the child at the time of diagnosis.
• The stage of the cancer.
• Whether the cancer has spread to the brain or spinal cord.

The prognosis for clear cell sarcoma of the kidney depends on the following:

• The age of the child at the time of diagnosis.
• The stage of the cancer.